1. Field of the Invention
This invention relates to a disc cartridge for housing a disc-shaped recording medium, such as a magnetic disc, and a dust-proofing system having the disc cartridge and a disc drive device for recording and/or reproducing the information for this disc cartridge.
2. Description of the Related Art
There has so far been known a disc cartridge rotationally housing a magnetic disc in its main body unit. Among known disc cartridges of this type, adapted to be removable, there is, for example, a disc cartridge having, as an information recording medium, a magnetic disc, 3.5 inch in diameter, having a signal recording layer on a flexible disc substrate, that is, a so-called flexible disc.
A disc drive device, loaded with this type of the disc cartridge and adapted to record and/or reproduce information signals for the magnetic disc, includes a head mechanism for supporting a head unit having a magnetic head element adapted for recording and/or reproducing information signals for the signal recording surface of the magnetic disc. The disc drive device also includes a movement mechanism for causing movement of the head unit via head mechanism along the radial direction of the magnetic disc, and a disc rotating and driving mechanism having a disc table on which to set the magnetic disc and a spindle motor for rotationally driving the disc table.
The disc drive device also includes a front panel having a cartridge insertion and/or removal opening via which to insert or remove the disc cartridge with respect to the main body unit of the device. The front panel includes an opening and/or closure door adapted for opening or closing the cartridge insertion and/or removal opening. This opening and/or closure door is rotatable towards the inside of the device and closes the cartridge insertion and/or removal opening in a state in which the disc cartridge is not loaded within the main body unit of the device.
If, in the disc drive device, constructed as described above, the disc cartridge inserted via the cartridge insertion and/or removal opening of the front panel, is loaded within the main body unit, the magnetic disc in the disc cartridge is set on the disc table and run in rotation. A head unit of the head mechanism then is moved by a movement mechanism along the radial direction of the head unit to record and/or reproduce the information signals for the magnetic disc by the head unit.
Meanwhile, with the recent trend towards the larger capacity of information signals, there has been proposed a large-capacity disc cartridge housing therein a magnetic disc improved in recording density so as to have a recording capacity of from tens to hundreds of megabyte in comparison with the conventional recording capacity of 2 megabyte. This large-capacity disc is referred to below as the large-capacity disc.
In the large-capacity disc, housed in the large-capacity disc cartridge, the track pitch and the track width are reduced to improve the density of recording tracks formed on the signal recording surface. Thus, the large-capacity disc suffers from the problem that, if fine dust and dirt have become affixed to the signal recording surface, the information signals cannot be recorded and/or reproduced accurately.
In this type of the large-capacity disc cartridge, a mistaken recording inhibiting hole is formed in a main cartridge body unit housing the large-capacity disc for controlling overwriting of information signals on the large-capacity disc. The large-capacity disc cartridge also has a detection hole adapted to be detected by detection means provided on a disc drive device of different specifications on loading the disc cartridge on this disc drive device of the different specifications for inhibiting recording of the information signals on the large-capacity disc to prohibit inadvertent erasure of information signals recorded to high density on the large-capacity disc.
In the above-described conventional large-capacity disc cartridge, the mistaken recording inhibiting hole and the detection hole are bored in the upper and lower cartridge halves, making up the main cartridge body unit, so that both ends of the holes are opened in the major surfaces of the upper and lower cartridge halves. In this type of the large-capacity disc cartridge, since the opening and/or closure door of the cartridge insertion and/or removal opening of the main cartridge body unit is rotated towards the inside of the main body unit of the device so that an end of the opening and/or closure door is abutted against the major surface of the main cartridge body unit, there is raised a problem that the cartridge opening and/or closure door is left open during recording and/or reproduction.
Therefore, in the above-described disc cartridge, since the mistaken recording inhibiting hole and the detection hole are proximate to the cartridge insertion and/or removal opening on loading the disc cartridge in the main body unit of the disc drive device, dust and dirt intruded via the cartridge insertion and/or removal opening, opened to outside of the disc drive device, are intruded via one opening ends of the mistaken recording inhibiting hole and the detection hole and via the insides of the holes and the other opening ends of the holes to turn around over and become affixed to the signal recording surface of the large-capacity disc within the main cartridge body unit to produce errors in the recording and/or reproducing operation for information signals.